Analysis of Short-Term Steel Corrosion Products Formed in Tropical Marine Environments of Panama (original) (raw)
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Corrosion study of steels exposed over five years to the humid tropical atmosphere of Panama
Hyperfine Interactions, 2017
The results of assessing five-year corrosion of low-carbon and conventional weathering steels exposed to the Panamanian tropical atmosphere is presented. Two different test sites, one in Panama City: 5 km from the shoreline of the Pacific Ocean, and another in the marine environment of Fort Sherman, Caribbean coast of Panama; namely, Fort Sherman Coastal site: 100 m from coastline. The corrosion products, formed in the skyward and earthward faces in the studied tropical environment, were mainly identified using room temperature and low temperature (15 K) Mössbauer spectroscopy, and ATR-FTIR. In all samples, lepidocrocite (γ-FeOOH) and goethite (α-FeOOH) were the main constituents. Some maghemite (γ-Fe 2 O 3), was also identified in Tocumen by Mössbauer spectroscopy and traces of feroxyhyte (δ-FeOOH) using ATR-FTIR. The corrosion rate values obtained are discussed in light of the atmospheric exposure conditions and atmospheric pollutants.
Hyperfine Interactions, 2009
The phases and compositions of the corrosion products of a mild steel (A-36) and two weathering steels (A-588 and COR 420) formed after 3 months exposure to the tropical marine atmosphere of Panama were examined using FTIR and Mössbauer spectroscopy. The results show that amorphous or crystallized iron oxyhydroxides goethite α-FeOOH and lepidocrocite γ-FeOOH are early corrosion products. Maghemite γ-Fe2O3 and magnetite Fe3O4 have also been identified and found to be prominent components for steels exposed to the most aggressive conditions. The formation of akaganeite β-FeOOH was observed when chlorides were occluded within the rust. FTIR showed the presence of hematite α-Fe2O3 in one sample.
Indoor atmospheric corrosion of conventional weathering steels in the tropical atmosphere of Panama
Hyperfine Interactions, 2014
One year indoor atmospheric corrosion examinations have been carried out on two conventional weathering steels for a year, at two test sites, Tocumen and Sherman Breakwater in Panama. They are environmentally classified by ISO 9223 as S 1 P 0 τ 4 and S 3 P 0 τ 5 , respectively. In this humid-tropical marine climate corrosion rates are rather high, especially at Sherman Breakwater test site, mainly due to the high deposition of chloride, among other environmental conditions. Our results indicate that indoor corrosion is highly determined by the time of wetness and chloride ions. A-588 weathering steel corroded at a generally lower rate than COR-420 weathering steel. Rust characterization was performed by XRD, FTIR, and Mössbauer spectroscopy. Lepidocrocite, goethite, maghemite and akaganeite were found as corrosion products. Akaganeite is only detected when high chlorides deposition rates are obtained, and no washing effect occurs. This phase, together with maghemite, is obtained when there is greater aggressiveness in the environment.
Corrosion Reviews, 2001
Rust scales of commercially available low carbon steels from Venezuela (A1S1 1010), Mexico and Cuba (A1SI 1019) were characterised after exposure at two typical atmospheres in the Caribbean region: Merida (rural-urban; RU) and Progreso (marine-coastal; MC). Low carbon steel surfaces rusting in those atmospheres formed mainly the oxyhydroxides lepidocrocite (γ-FeOOH), goethite (α-FeOOH) and akaganeite (ß-FeOOH). Different amounts of lepidocrocite, goethite and akaganeite and the oxide phases hematite (a-Fe 2 0 3), magnetite (Fe 3 0 4) and maghemite (y-Fe 2 0 4) were found, depending on the deposition rates value of airborne salinity, time-of-wetness (TOW) and temperature present in every particular test site. The rust scale composition and air pollution are used to explain the corrosion rates and corrosion behaviour of the exposed low carbon steels in the tests sites. 435
Evaluation of Steel Corrosion Products in Tropical Climates
CORROSION, 1997
Phase variations occurring in corrosion products obtained in steels exposed to different zones of tropical climate in Cuba and Venezuela were determined to establish their relationship to corrosion phenomena. Steel corrosion products were obtained at four test stations in both countries with marine, industrial, and rural characteristics. Phase composition was determined using x-ray diffraction (XRD), infrared (IR) spectroscopy, and Mössbauer spectroscopy. In the rural climate of both countries, the predominant phase was lepidocrocite (␥-FeOOH), which was in agreement with reported corrosion rates. In the marine environments, corrosion products varied in composition. In Adicora, Venezuela, akaganeite (-FeOOH) was found, but in Cuba, this phase was nonexistent. Results were discussed in light of the contamination present and meteorological parameters recorded in the test zones.
Industrial Applications of the Mössbauer Effect, 2002
ASTM 283-C, AISI 304 and 316-L steel specimens (called coupons) were exposed in marine, industrial and rural area(s) for different periods ranging between 1-12 months, in four different season campaigns. The corrosion rate was determined by chemical loss measurements. Rust characterization was performed by XRD, SEM, optical, and Mössbauer spectroscopy (in transmission and backscattering geometry). Superparamagnetic maghemite and goethite were found as corrosion products. Magnetic goethite and feroxyhite decrease with time of exposure. Lepidochrosite is detected and its intensity increase with the atmospheric exposure time. The results obtained from XRD and Mössbauer are in good agreement.
Atmospheric corrosion of different steels in marine, rural and industrial environments
Corrosion Science, 1999
The atmospheric corrosion of the dierent steels at the dierent exposure conditions has been investigated by MoÈ ssbauer and Raman spectroscopies and XRD. Goethite and lepidocrocite were identi®ed in the corrosion products formed on all the coupons. Magnetic maghemite, which resulted in the high corrosion rate, formed on the carbon steel exposed at the marine site. The inner layer, a protective layer, mainly consisted of interdispersed goethite, and the outer layer mainly composed of interdispersed lepidocrocite. The larger fraction of superparamagnetic goethite, which resulted in decreasing the mean particle size of goethite, in the corrosion products was closely related to reduction in the corrosion rate in the marine and rural sites. The larger amounts of silicon and smaller amounts of phosphorus in the steel increased the fraction of superparamagnetic goethite. However, dierent amounts of nickel did not aect the formation of the iron oxides after sixteen years of exposure.
Atmospheric corrosion of mild steel in chloride-rich environments. Questions to be answered
Materials and Corrosion, 2014
This paper describes the peculiarities of carbon steel corrosion in very severe marine atmospheres and points out a number of uncertainties that still need to be explained, such as the following: (a) Data on the evolution of carbon steel corrosion (C) with exposure time (t) obeys the power function C ¼ At n. The variables upon which n depends are not fully known, though the salinity of the atmosphere undoubtedly plays a prominent role. (b) In marine atmospheres, the presence of akaganeite and magnetite phases among the corrosion products is especially significant. In relation with these corrosion products, a number of important questions remain unanswered: What conditions are necessary for their formation? Where are they preferentially located? Is there a critical atmospheric salinity concentration below they are unlikely to form? It is also of great interest to know the typical surface microscopic morphologies resulting from the presence of akaganeite, where the confusion among researchers is well known. (c) In very severe marine atmospheres, the morphology of the corrosion layers formed on steel can be highly unusual, such as sheet-type or mound rust. There is a lack of basic knowledge on the formation mechanisms and internal microstructure of these rust types.
A Study of the Atmospheric Corrosion Products on Steel
Corrosion & Prevention Conference paper 24, 1990
Investigations into the chemical composition of corrosion products on steel has shown that rust grown under laboratory conditions consist mainly of lepidocrocite with small amounts of goethite and magnetite. Under highly corrosive conditions, the rust is much thicker and a significant amount of magnetite forms under an outer layer of lepidocrocite.
Corrosion behavior of weathering steel in tropical atmosphere of Vietnam
— Weathering steel (WS) of Corten B type was exposed for three years at three test sites including urban and marine sites. After one year-exposure, WS showed the protective ability better than carbon steel (CS) did. The corrosion loss of WS fitted well power law with high correlations. The characterization of rust layer was studied by using X-ray diffraction, optical microscope and SEM-EDX. Goethite (α-FeOOH), akaganeite (β-FeOOH), lepidocrocite (γ-FeOOH), maghemite and magnetite were founded in corrosion product formed on WS for 3, 6, and 12 month-exposure; The structure of rust layer of WS composed of two layers – the inner layer dark-grayish, dense and good adherent to steel substrate; and the outer layer porous and reddish; The morphologies of rust surface showed the sandy and flowery structure typical for lepidocrocite and cotton balls structure typical for goethite; Cr and Cu distributed in the inner layer of rust – at distance of 40-60µm from steel substrate. The resistance of rust layers was evaluated by using electrochemical impedance spectroscopy measurement. This proved the predominance of WS over CS in corrosion resistance. The influence of environmental factors on protectiveness of WS was also discussed in this paper.